Mushroom cultivation is increasingly becoming popular because it not only meets the dietry requirements but also adds to the income, especially of growers with insufficient land. It is considered to be a very rewarding and fascinating hobby for the retired persons as well as house-wives who can grow mushrooms in small boxes or other containers while attending to household chores. Today, mushroom cultivation faces less difficulties provided the grower will follow simple rules of growing.

It is really amazing that a small quantity of spawn when planted in suitable growing medium can, within almost six weeks, grow into a highly profitable crop inside a room, where no other crop would grow. Moreover, mushrooms have more uses in modern culinary cuisine than any other food crop. Mushroom cultivation is carried out indoor in any room, shed, basement, garage, etc. which should be well ventilated. However, paddy straw mushroom can be grown outside in shady places also.

Of the many mushrooms only three kinds namely button mushroom (Agaricus bisporus), straw mushroom (Voluariella uoluacea) and oyster mushroom (Pleurotus sajor-caju) are suitable for cultivation in India.

Button mushroom is grown in winter. The most suitable temperature for the spread of the mycelium is 24-25°C, while 16-18°C is essential for the formation of fruit bodies.Higher temperature is harmful and low temperature retards the development of both mushroom mycelium and fruit bodies.

Paddy straw mushroom can be grown around 35°C. Temperature should not go below 30°C or above 40°C for more than 4-8 hours during growing period. In northern India it can be grown from April to September but the most suitable period is from middle of June to middle of September.

Dhingri (oyster mushroom) grows best between 22-28°c. It is grown in northern plains from October to March.

The methods of cultivation of these three mushrooms are given separately.

BUTTON MUSHROOM

The cultivated mushroom is grown on special composts, which are of the following two types, synthetic and natural.

Composting yard

The compost should be prepared on well cleaned concrete or pucca floor, which should be at a higher level so that the run-off water does not collect near the heap.Composting is usually done in the open, but it has to be protected from rain by covering it with polythene sheet. It can also be done in a shed with open sides or a large room to shelter it from rain.

1. Synthetic compost

The following ingredients are required for 15-16 trays of size 100cmx50cmx15cm:-

The straw is uniformly spread over the compo sting yard in a thin layer and wetted thoroughly by sprinkling water. All ingredients such as wheat bran, fertilizers, etc. except gypsum, are mixed thoroughly in the wetted straw, which is finally heaped into a pile. The pile, 1m high, 1m wide and length adjustable, can be made with hand or stack mould. The straw should be firmly but not compactly compressed into the mould.

It is essential to open the entire pile and remake it a number of times according to the following schedule:

Mixing of material and making pile - 0 day

1st turning - 4th day

2nd turning - 8th day

3rd turning - 12th day, add 10 kg gypsum

4th turning - 16th day, add 10 kg gypsum

Final turning - 20th day, spray 10 ml malathion in 5 litre water (any other available pesticide like DOT, BHC, lindane can also be used)

At each turning water should be sprinkled to make up the loss of water due to evaporation. If it is desired to add molasses, then 10 kg molasses diluted 20 times with water should be poured over the straw mixture during the first turning. Sixty kg chicken manure, if available, can also be added at the time of start of pile.

2. Natural compost

The following ingredients are required for 15-16 trays of size 100cmx50cmx15cm:-

It is prepared from pure horse dung (dung of other animals should not be admixed), which must be freshly collected and should not have been exposed to rain. Chopped wheat straw is mixed with horse dung, urea or poultry manure. The mixture is uniformly spread over the compo sting yard and water is sprinkled over it so that the straw becomes sufficiently wet. The manure is then heaped in a pile as for synthetic compost. After 3 days when the manure in the heap gets heated up due to fermentation and gives off an odour of ammonia it is opened. The process is repeated 3 or 4 times after an interval of 3-4 days. Twenty five kg gypsum per tonne is added in two instalments at the 3rd and 4th turning. At the final turning 10 ml malathion diluted in 5 litres of water is sprayed into the manure.

Compost Filling in trays:

The compost when ready for fil1ing and spawning has a dark brown colour and no trace of ammonia. There is no unpleasant odour but it smells like fresh hay. The pH is neutral or near neutral. The compost should not be too dry or too wet at the time of filling in the trays, which can be determined by the palm test. For this purpose a small quantity of compost is taken into the hand and pressed lightly, if a few drops of water ooze out of the fingers then it is of right consistency. If relatively dry then the water should be made up by sprinkling. If too wet, the excess water should be allowed to evaporate. The prepared compost is now filled in trays, which may be of any convenient size but depth should be 15-18 cm. A standard size of tray is 100 cm x 50 cm x 15 cm. The trays should be made of soft wood and provided with the pegs at the four corners so that they can be stacked one over the other leaving sufficient space (15 cm) between the two trays for various operations. The trays are completely filled with the compost, lightly compressed and the surface levelled.

Spawning

Spawning means sowing the beds with the mycelium (spawn) of the mushroom. Spawn can be obtained from Mushroom Laboratory, Y. S. Parmar University, Chambaghat, Solan; National Mushroom Research and Training Centre, Chambaghat, Solan (H.P.) at a nominal cost. Small quantity of spawn is also available from the Division of Mycology and Plant Pathology, Indian Agricultural Research Institute, New Delhi.

The grain spawn is scattered on the surface of the tray bed which is covered with a thin layer of compost. Spawning can also be done by mixing the spawn with compost before filling it in trays. Five hundred gram spawn is sufficient for five trays of standard size. After spawning, the compost surface is covered with old newspaper sheets, which are wetted by sprinkling water to provide humidity but no water is directly added to the compost during spawn running.

The trays after spawning are stacked vertically one over the other in 4-5 tiers. One metre clear space may be left in between the top tray and ceiling. There should be about 15-20 cm space between the two trays.

The room should be maintained around 25°c. The humidity should be built up by frequently watering the floor and walls. The room may be kept closed as no fresh air is needed during the spawn run. White cottony mycelium spreads and permeates through the compost. Eventually the compost surface gets covered with the mycelium. It takes 12-15 days for complete spawn run. Low temperature prolongs the spread of the mycelium.

Casing

After the spawn run is complete as is evident by white cottony growth, the surface of the compost is covered with 3 em layer of casing soil. A suitable casing soil can be prepared by mixing equal parts of well rotten cowdung (finely crushed and coarsely sieved) and garden soil. The casing material should possess high water holding capacity, good pore space and pH should not be lower than 7.4. The casing material is sterilized to kill insects, nematodes and molds. Sterilization can be accomplished either by steaming or by treating with formalin solution. For one cubic metre of casing soil, hqlf litre for formalin (40%) diluted with 10 litre of water is sufficient. The casing soil is spread over a plastic sheet and treated with formalin by sprinkling. The treated soil is piled up in a heap and covered with another plastic sheet for 48 hours. The soil is turned frequently for about a week to remove all traces of formalin which can be tested by smelling. After casing, the temperature of the room is maintained at 25°C for further three days, after which it must be lowered to below 18°C. At this stage lot of fresh air is needed and, therefore, the growing room should be ventilated by opening windows etc.

Cropping and HalVesting

The first flush of the pin heads become visible 15-20 days after casing or 35-40 days after spawning. Small white buttons develop 5-6 days after pin head stage. The right stage of harvest is when the caps are still tight over the short stem. In case the buttons are allowed to mature further, the membrane below the cap will rupture and the cap will open up in umbrella-like shape. Such mushrooms are considered to be inferior. Harvesting is done by holding the cap with forefingers slightly pressed against the soil and twisting it off. The soil particles and mycelial threads clinging to the base of the stalk are chopped off. Mushroom can also be harvested by cutting off with a sharp knife at soil level.

Yield

The average yield of 3-4 kg per tray is considered normal. However, if compost is carefully prepared, spawn is reliable and temperature is favourable, then a yield of 5-6 kg per tray is possible. Partial or complete failure may also happen due to negligence.

Storage

The mushrooms are best consumed fresh. Storage in refrigerator for a few days is possible if they are placed between moist paper towel.

PADDY STRAW MUSHROOM

Paddy straw mushroom, also called Chinese Mushroom (Volvariella spp.) is grown in South-East Asia. This mushroom is dark in colour and is very delicious. It is usually grown in raised beds, which are laid in open, exposed or shady places over which temporary sheds are built to protect the beds from direct sunlight and rain. If the beds are made indoors in a well ventilated room which is not very dark, the production of mushrooms is more steady and reliable.

Spawn of Paddy straw mushroom

Spawn of this mushroom is made on grains of cereals or millets and is called grain spawn. Sometimes it is also made on soaked chopped paddy straw. This spawn is called straw spawn. Spawn may be available locally from the Division of Mycology and Plant Pathology, Indian Agricultural Research Institute, New Delhi-llOO12 at nominal price. Spawn is also available from Plant Pathology or Microbiology Departments of the respective Agricultural Universities. One bottle of spawn is sufficient for one bed.

Substrate or Bedding Material

This mushroom is usually grown in paddy straw. Thoroughly dried and long paddy straw is preferred. The straw is tied in bundles of about 8-10 cm in diameter. The bundles are then cut to a uniform length of about 70-80 cm, and are soaked by immersing them in a tank of water for about 12-16 hours. Later, excess water is allowed to drain off.

Procedure for making the bed:-

Make a 15-20 cm h)gh foundation of soil or bricks. The size of the foundation is slightly larger than that of bed. The foundation must be strong and firm to hold the weight of the bed.

- Make wooden bamboo frame of the size of the bed foundation and place it on top of the raised bed foundation.

- Place four bundles of soaked straw side by side on the wooden/bamboo frame.Over these, place another set of four bundles similarly but the loose ends on the opposite side. These 8 bundles consitute the first layer.

- Scatter grain spawn about 8-12 cm from the edges of the first layer. If straw spawn is used, small pieces of the size of the thumb are planted about 4-6 cm deep and about 10-15 cm apart along the edges. Dust the spawn with powdered gram/arhar dal powder or rice/wheat bran.

- Now place a second layer of eight bundles across the first layer and spawn it as before.

- Again place a third layer of straw bundles across the second layer and spawn it all over the surface.

- Finally cover with a fourth layer of four straw dundles. Press it lightly.

- Completely cover the bed with a transparent plastic sheet, taking care that the plastic sheet is not in contact with the bed.

Care of bed

Remove the transparent plastic sheet after the mycelium has thoroughly permeated the straw. This would take about a week at 35°c. If the surface of the bed gets dry then it should be watered lightly by a sprayer at least once a day.

The Crop

Mushrooms begin to appear within 10-15 days after the beds are spawned and continue to do so for about a week or 10 days. The total yield of the bed is about 2-2.5 kg. The mushrooms should be picked when the volva (cup like veil) just breaks to expose the mushroom inside. The mushrooms are very delicate and must be consumed fresh. If stored in fridge they can stand for 2-3 days. These mushroo~s can easily be air dried in sun or shade.

OYSTER MUSHROOM

This mushroom is simple to grow and has excellent flavour and texture. It is very popular in many countries particularly in South-East Asia, where cultivation of button mushroom (Agaricus bisporus) is not possible under natural climatic conditions. Besides its delicious taste, it is known to be very nutritious and is recommended to control obesity and is reported to be beneficial for diabeties. Its low fat content makes it an ideal diet for the blood pressure patients.

Substrate or growing material

It can be cultivated on a wide ranging of cellulosic farm wastes or other materials. Cereal straws, banana pseudostems, waste paper, cotton waste are particularly suitable.However, paddy straw is the most commonly used material.

1. Oyster growing in polythene bags

Paddy straw is chopped into small pieces 3-5 cm long. It is soaked in water for . about 8 hours, after which water is squeezed out.- About 200 g grain spawn (half litre bottle) is mixed thoroughly with about 5-6 kg of wet chopped straw (= lY2 kg dry straw).- A polythene bag 45 cm long and 30 cm diam. is used. It is perforated with 2 mm diam. holes, about 4 cm apart, all over the surface. Spawned straw is filled about 2/3rd of the capacity of the bag and mouth tied.- The bags containing spawned straw are placed in shelves in the growing room (RH. 80-85% and room temperature 24-26°C).

2. Growing in rectangular blocks

A wooden tray mould (50 cm x 33 cm x 15 cm) without bottom is required. A one m2 piece of transparent polythene sheet is spread so that it forms the bottom of the tray mould and also lines the sides from inside. The loose edges hang out from the tray mould.- Fill in the wetted chopped paddy straw (as described for bag method above) to make a 5 cm thick bottom layer. Scatter spawn uniformly. Lay another 5 cm thick layer over the top of bottom layer and spawn it in the same way. Finally, lay the third layer (final layer) over the second and repeat spawning. Spawn is covered with more wetted straw to bring it in level with the top of the mould. Compress it firmly by hands or a board. Two hundred grams (Yz litre bottle) spawn is sufficient for two blocks.- Fold the loose hanging edges of plastic sheet over the straw block, fasten with a string. Remove the rectangular block from the mold.

Spawn Run

The spawned bags/blocks are placed on shelves in the growing room where RH. is maintained at 80-85 per cent and room temperature is about 24-26°C.- Spawn run is complete in about 10-12 days and is indicated by white cottony mycelium which permeates throughout the straw. As a result the straw becomes compact and does not split when handled. At this stage, polythene covering is removed by cutting it open in case of bags and by untying the polythene sheet in case of blocks. In case of bags, the straw gets compacted in the form of a cylinder.- The cylinder/blocks are neatly arranged on shelves and gently watered at least twice a day.

The Crop

First mushrooms appear about 18-20 days after spawning. Two or three flushes appear at an ,interval of about a week. Dhingri should be harvested when the cap starts becoming folded. Harvesting can be done by cutting with a sharp knife or by twisting it off with fingers from the substrate. Dhiilgri is best consumed fresh. It can be dried in sun or in a mechanical drier, and stored in polythene bags.

Yield

About one kg mushroom can be obtained from 1Yz kg dry straw (=5-6 kg wet straw).